Location
Diamond 122
Start Date
1-5-2014 1:00 PM
End Date
1-5-2014 4:00 PM
Project Type
Presentation
Description
The Messalonskee Stream in central Maine has five hydroelectric dams on 16.6km. Each dam drastically changes the flow regime of the stream, dividing it into segments with different patterns of sediment settling and organic matter retention. We investigated how these disruptions impact nitrogen cycling, specifically nitrification rates above and below each dam. We expected higher nitrification rates above the dams, where levels of organic matter are higher, and lower rates below the dam where scouring removes organic matter and fine sediment from the streambed. We measured sediment nitrification rates with a nitrapyrin-inhibition assay and potential drivers of nitrification including sediment organic matter and pore water ammonia (NH4+) above and below each dam. Nitrification rates ranged from below detection to 552 μg NH4+ gAFDM-1 day-1 with no consistent pattern between above and below sites. Variation among the five dam sites is due different distributions of sediment above and below the dams and widely varying flow velocity.
Faculty Sponsor
Russ Cole
Sponsoring Department
Colby College. Environmental Studies Program
CLAS Field of Study
Interdisciplinary Studies
Event Website
http://www.colby.edu/clas
ID
659
The Impact of Dams on Nitrogen Cycling in the Messalonskee Stream
Diamond 122
The Messalonskee Stream in central Maine has five hydroelectric dams on 16.6km. Each dam drastically changes the flow regime of the stream, dividing it into segments with different patterns of sediment settling and organic matter retention. We investigated how these disruptions impact nitrogen cycling, specifically nitrification rates above and below each dam. We expected higher nitrification rates above the dams, where levels of organic matter are higher, and lower rates below the dam where scouring removes organic matter and fine sediment from the streambed. We measured sediment nitrification rates with a nitrapyrin-inhibition assay and potential drivers of nitrification including sediment organic matter and pore water ammonia (NH4+) above and below each dam. Nitrification rates ranged from below detection to 552 μg NH4+ gAFDM-1 day-1 with no consistent pattern between above and below sites. Variation among the five dam sites is due different distributions of sediment above and below the dams and widely varying flow velocity.
https://digitalcommons.colby.edu/clas/2014/program/351